WordPress site not accessable from the Internet

Since we changed our ISP network and router, my word press site will not display on the Internet. It times out. Me and Cisco Tech support have spent many hours trying to discover what could be the issue.

The DMZ network and server remained the same:
– Same static private IP address, SNM, DNS server 8.8.8.8, same Internet name servers.
– The WordPress server is a TurnKeyLinux (Debian) Lamp build with WordPress separately installed.
– WordPress version 4.1.1 using a network
– We are using the Progression Studios 0Pixel theme.
– We have bbPress, Download Manager, Easy Pricing Tables Lite, Google Analytics, Visual Form Builder, and YouTube Plugins

This is what changed on 3/6/2015:

– The default gateway on the server
– The Public IP address on the Internet name servers
– The Cisco router

Factors:
– Our Window IIS servers are work just fine, no issues
– I switch the WordPress server’s IP with a Windows IIS server’s which was working. The WordPress Server still didn’t work from the Internet
– Cisco has done packet analyst of traffic on the server and on the router. It appears that all the right traffic is getting through in both directions
– The WordPress site works from within the DMZ network, and from the trusted network with the private IP address placed in hosts files on PCs
– The Linux server pings outside sites by domain name

Can anyone suggest something that might be the issue?

Thanks,

Ken